All law-breaking hedge-fund traders should live in downtown duplex lofts, where they can cackle by the wood-burning fireplace or their tropical aquarium. And their condo buildings should all have decadent names like Sugar Warehouse.

Steven B. Markovitz, a trader that admitted four years ago to illicitly buying and selling mutual funds while the market was closed, has sold his 3,555-square-foot apartment in the Sugar Warehouse Condominium at 79 Laight Street. According to city records, the 26-year-old fashion designer Erin Fetherston paid $4.33 million for the three-bedroom loft earlier this month.

Listing broker Susan Gilder Hayes, a Corcoran Group vice president, wouldn’t discuss the deal, but she said: “The owner had the most beautiful aquarium put in the house. And it had all these great tropical fish in it! But a lot of people that were going to buy didn’t like the idea that they had to care for live fish.”

So the fish aren’t there anymore. But once there was everything from “spider crawly fishes to beautiful blue ones; interesting crabs that would come out; some of the most beautiful coral I’ve ever seen,” the broker said.

That’s what you get when you work for a $4 billion fund like Millennium Partners. But Mr. Markovitz left that firm in 2003 after an investigation by then Attorney General Eliot Spitzer; the S.E.C. banned him for life from associating with investment advisers, and fined him a few hundred thousand dollars, too.

As for his buyer, The Observer profiled Ms. Fetherston just last week. She and her fiancé, an artist, will apparently keep a pied-à-terre in Paris. “The values of my collection—a sense of whimsy, a sense of romance, girly-cute style—there are a handful of celebrities who to me totally embody that,” she said, “and I adore them.”

Speaking of which, the listing broker, Ms. Hayes, an ex-model, is married to the majestic attorney Ed Hayes, who inspired the Tommy Killian character in Tom Wolfe’s The Bonfire of the Vanities. She said the apartment opens to a clear-glass gate (with iron decorations) and full-on Hudson River views: “You get off the elevator; you walk out, and immediately go, ‘Oh my God. Wow.’”